Political optimism has been tempered by allegations of polling station intimidation as voting in the General Election entered full swing in Scotland.

SNP heavyweight Alex Salmond insisted his party's "tails are up across the country" as he cast his vote in Ellon, in the Gordon constituency where he is standing.

Mr Salmond joined SNP voter Nicki Falconer, who voted for the first time in last year's independence referendum and has since joined the party.

SNP leader Nicola Sturgeon said Scotland's political future is now "in the hands of the voters" after voting early at Broomhouse community hall in Glasgow accompanied by husband and SNP chief executive Peter Murrell.

But Scottish Conservative leader Ruth Davidson took to Twitter with allegations of voter intimidation in Dumfriesshire, Clydesdale and Tweeddale, where Scotland's only Tory MP David Mundell is hoping for a return to Westminster.

She said: "Disturbing reports of people being turned away from an Annan polling station by burly blokes if they say they don't support a certain party."

Police Scotland and Dumfries & Galloway Council said they are currently looking into the allegations.

Scottish Labour leader Jim Murphy said "the sun is shining and there is a huge amount of energy and confidence" in the party as he voted at Busby Primary School in the East Renfrewshire constituency he has represented since 1997.

"I've always been the underdog in this constituency," he said.

"It's usually the Tories who are favourites but the bookies say this time round it's the SNP, but I always enjoy confounding the pollsters, the pundits and the bookies. We've had a great response."

Former Labour shadow foreign secretary Douglas Alexander said "a Labour government is within touching distance" as the polls opened in Paisley and Renfrewshire South while his SNP opponent Mhairi Black urged people to "vote for a fresh start".

Liberal Democrat Equalities Minister Jo Swinson said it had been "a glorious start to polling day" in East Dunbartonshire.

David Coburn MEP, Ukip's only elected politician in Scotland, also voted in Edinburgh before setting off for a round of broadcast interviews.

In response to the Scottish Conservative leader's claim, a police spokesman said: "Police Scotland is aware of the tweet from Ruth Davidson and is looking into the matter."

A spokesman for the Scottish Conservatives said: "Two members of the public complained to us regarding a situation at Newington Sports and Leisure Polling Station in Annan.

"We have passed on their complaint to the electoral registration officer at the council and have spoken to Police Scotland. We take all such reports seriously and always pass on the relevant information."